Fix: Enhance robustness and clarity in kg-solver components

[thesteganos]

This commit addresses several issues identified during a code analysis, focusing on improving the robustness, error handling, and clarity of various components within the KAG solver.

The following changes have been made:

1. KAGIterativePlanner:

   • Corrected is_static() method to return False, aligning with its iterative behavior.

2. KAGRetrievedResponse:

   • Removed a misleading note about an f-string formatting error from the to_string() method's docstring, as the error was not present in the code.

3. KAGStaticPlanner:

   • Improved finish_judger error handling: If the LLM call to judge the answer fails, it now logs a warning and returns False (treating the answer as potentially bad) instead of defaulting to True.

4. ChunkRetrievedExecutor:

   • Clarified schema name: Changed the name field in its schema dictionary from "Retriever" to "ChunkRetriever" to better differentiate it from other retriever executors like KagHybridExecutor.

5. PyBasedMathExecutor:

   • Added a configurable timeout (defaulting to 5 seconds) to the subprocess.run() call within the run_py_code function. This prevents indefinite hangs from long-running or stuck Python scripts generated by the LLM. Includes handling for subprocess.TimeoutExpired.

6. DefaultStaticPlanningPrompt:

   • Enhanced parse_response method: Implemented more robust JSON decoding and structural validation for the LLM-generated DAG plan. It now raises more descriptive ValueError exceptions, including details of the malformed data, when KeyError or TypeError occurs during task creation from the DAG, aiding in debugging.